Mycoplasma genitalium has been found to be associated with nongonococcal urethritis in men and there is some evidence to suggest that it may be a significant pathogen in women as well. It has been associated with mucopurulent cervictis in two studies. The major complication of bacterial STIs in women is infection of the upper genital tract resulting in pelvic inflammatory disease (PID) and fallopian tube scarring, which in turn cause ectopic pregnancy and/or infertility. There are a few reports suggesting that M. genitalium also causes these complications but these studies have not yielded consistent results. One serologic study suggests that the organism is associated with "tubal factor" infertility. If this should in fact turn out to be true then M. genitalium will be added to the list of significant bacterial STIs that should be prevented through effective treatment of symptomatic individuals and their sexual partners and by screening and treatment of asymptomatic high risk women and men. We will address this important issue in the first two Aims of this study as follows: 1. We will study a group of infertile women with and without fallopian tube disease drawn from a high STI risk population in New Orleans using our well established MG PCR assay and a specific serologic assay using recombinant M. genitalium lipoprotein antigens that we will develop. 2. We will study women at high risk of becoming infertile enrolled in a randomized infertility prevention treatment trial. Finally, in the third Aim we will study genetic mechanisms that this organism may use to escape the host immune system using specimens obtained from chronically infected chimpanzees and humans.